The present invention relates to a method for assembling an actuator device for a hard disk, the actuator comprising a read/write transducer, a microactuator, and a suspension, and the actuator device obtained using the method.
As is known, an actuator device for a hard disk recently has been proposed. The actuator device is provided with a double actuation stage to finely control a position of a read/write head with respect to the hard disk to be read or written. An example of a known actuator device 1 with a double actuation stage is shown schematically in FIGS. 1 and 2. In detail, in FIG. 1, the actuator device 1 for a hard disk 7 comprises a motor 2 (also called a xe2x80x9cvoice coil motorxe2x80x9d), to which at least one suspension 5 formed by a lamina is fixed in a projecting manner. At its free end, the suspension 5 supports a read/write (R/W) transducer 6 (see, e.g., FIG. 2) (also known as a xe2x80x9csliderxe2x80x9d) which in an operative condition, is disposed facing a surface of the hard disk 7 (see, e.g., FIG. 1). The R/W transducer 6 is rigidly connected to a coupling (called a xe2x80x9cgimbalxe2x80x9d 8), through a microactuator 9 interposed between the gimbal 8 and the R/W transducer 6. On one of its lateral surfaces, the R/W transducer 6, formed by a ceramic material body (e.g., AlTiC), further has a read/write head 10 (which is magneto/resistive and inductive) which forms the actual read/write device.
In the actuator device 1, a first actuation stage is formed by the motor 2 that moves an assembly formed by the suspension 5 and the R/W transducer 6 across the hard disk 7 during track seeking, and a second actuation stage is formed by the microactuator 9 that finely controls a position of the R/W transducer 6 during tracking.
An embodiment of the microactuator 9 of a rotary electrostatic type is shown in diagrammatic form in FIG. 3, wherein the microactuator 9 is shown only in part, given its axial symmetry. The microactuator 9 comprises a stator 17 integral with a die accommodating the microactuator 9 and bonded to the gimbal 8, and a rotor 11 intended to be bonded to the R/W transducer 6 and capacitively coupled to the stator 17.
The rotor 11 comprises a suspended mass 12 of a substantially circular shape and a plurality of movable arms 13 extending radially towards the outside from the suspended mass 12. Each movable arm 13 has a plurality of movable electrodes 14 extending in a substantially circumferential direction and spaced at a same distance from each other. The rotor 11 further comprises anchoring and elastic suspension elements (shown as springs 15) for supporting and biasing the rotor 11 through fixed regions 16.
The stator 17 comprises a plurality of fixed arms 18a, 18b extending radially and each bearing a plurality of fixed electrodes 19. In particular, associated with each movable arm 13 is a pair of fixed arms formed by the fixed arm 18a and the fixed arm 18b. The fixed electrodes 19 of each pair of fixed arms 18a, 18b extend towards the associated movable arm 13 and are intercalated or interleaved with the movable electrodes 14. The fixed arms 18a are all disposed on a same side of the respective movable arms 13 (on the right side in the example shown in FIG. 3) and are all polarized at a same potential via biasing regions 20a. Similarly, the fixed arms 18b are all disposed on the other side of the respective movable arms 13 (on the left side in the example shown in FIG. 3) and are all biased at a same potential through biasing regions 20b. The fixed arms 18a and 18b are biased at different potentials to generate two different potential differences with respect to the movable arms 13 and to cause the rotor to rotate in one direction or the other.
In the assembly of FIG. 2, there is a problem that the microactuator 9 is exposed to an external environment, and is therefore not protected against dielectric particles that can prevent the microactuator 9 from functioning satisfactorily. In addition, in the actuator device 1, electrostatic interference may arise between a high voltage (of approximately 80 V) used for the actuation and the read/write head 10, thus preventing, or at least jeopardizing, satisfactory functioning of the read/write head 10.
An advantage of the invention is to provide an actuator device that addresses the problems described above currently affect known devices.
According to embodiments of the present invention, a method is provided for assembling an actuator device for a hard disk, the actuator device comprising a read/write (R/W) transducer, a microactuator, and a suspension plate.
The method comprises connecting the microactuator to a first face of the suspension plate and projecting the R/W transducer from a second face of the suspension plate opposite to the first face. The connecting comprises placing a strip of adhesive material between a body accommodating the microactuator and the suspension plate and activating the strip.
In an embodiment of the invention, the suspension plate has a through-hole having a larger size than the R/W transducer. Before the connecting the microactuator to the first face of the suspension plate, the method further comprises assembling the R/W transducer to the microactuator and inserting the R/W transducer in the through-hole.